Network Mission critical electrical appliances require continuous and stable electricity supply. It is common that an electrical appliance is connected to two or more different electricity supplies. When one or more of the electricity supplies are out of order, the remaining electricity supplies hopefully may have adequate electricity to supply. For electrical appliances that requires direct current (DC) to operate, alternating current (AC) needs to be converted to DC by AC-DC regulators. AC-DC regulators are known to have reliability and stability problem. It is not uncommon to find AC-DC regulators failed while an electrical appliance is in operation.
Further an AC-DC regulator is connected to one electricity supply only. In the case of a failure, including a power failure of one electricity supply or an electricity supply is not connected to the electrical appliance, the corresponding AC-DC regulator to the electricity supply is not being used and become under-utilized. Comparing to normal operation, during a failure, AC-DC regulators of remaining electricity supplies are likely to be under heavier load as the remaining electricity supplies need to supply more power. The heavier load may cause problem with reliability and stability, and may also shorten the lifespan of the AC-DC regulators of remaining electricity supplies.
Further, when in case of a failure due to one or more electricity supplies and/or one or more AC-DC regulators, the remaining electricity supplies may not have enough capacity to supply the electrical appliance or the electrical appliance may not be able to perform functions that require large amount of electricity. When the electrical appliance continues drawing the amount of electricity from the remaining electricity supplies are not able to provide, this may result in safety hazard as it is possible that too much current is drawn from a particular electricity supply or too much load on one or more of the AC-DC regulators.
In the case that the electrical appliance is capable of providing electricity to other devices through power ports of the electrical appliance, the configuration and management of the electrical appliance and the power ports would be time consuming and prone to errors. Further, when redundancy and priority are required, the configuration and management will become more complicated.